USPTO Patents Application 10505241

\q (19) World Intellectual Property Organization

(12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)

20 AUG 2004

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International Bureau

(43) International Publication Date
18 September 2003 (18.09.2003)

PCT

(10) International Publication Number

WO 03/076534 Al

(51) International Patent Classification 7 : C09D 15/12,
B32B 15/08

(21) International Application Number: PCT/US03/06609

(22) International Filing Date: 5 March 2003 (05.03.2003)

(25) Filing Language: English

(26) Publication Language: English

(30) Priority Data:

60/362,058
60/373,151

5 March 2002 (05.03.2002) US
17 April 2002 (17.04.2002) US

(71) Applicant (for all designated States except US): CHEM-
NOVA TECHNOLOGIES, INC. [US/US] ; NIU Technol-
ogy Commercialization Office, Adams Hall 321, DeKalb,
IL 60115 (US).

(72) Inventor; and

(75) Inventor/Applicant (for US only): LIN, Chhiu-Tsu

[US/US]; Northern Illinois University, Department of
Chemistry and Biochemistry, DeKalb, IL 60115 (US).

(74) Agents: KOHN, Kenneth, L et al.; Kohn & Associates,
PLLC, 30500 Northwestern Highway, Suite 410, Farming-
ton Hills, MI 48334 (US).

(81) Designated States (national): AE, AG, AL, AM, AT, AU,
AZ, BA, BB, BG, BR, BY, BZ, CA, CH, CN, CO, CR, CU,
CZ, DE, DK, DM, DZ, EC, EE, ES, H, GB, GD, GE, GH,
GM, HR, HU, ID, IL, IN, IS, JP, KE, KG, KP, KR, KZ, LC,
LK, LR, LS, LT, LU, LV, MA, MD, MG, MK, MN, MW,
MX, MZ, NO, NZ, OM, PH, PL, PT, RO, RU, SC, SD, SE,
SG, SK, SL, TJ, TM, TN, TR, TT, TZ, UA, UG, US, UZ,
VC, VN, YU, ZA, ZM, ZW.

(84) Designated States (regional): ARIPO patent (GH, GM,
KE, LS, MW, MZ, SD, SL, SZ, TZ, UG, ZM, ZW),
Eurasian patent (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM),
European patent (AT, BE, BG, CH, CY, CZ, DE, DK, EE,
ES, FT, FR, GB, GR, HU, EE, IT, LU, MC, NL, PT, RO,
SE, SI, SK, TR), OAPI patent (BF, BJ, CF, CG, CI, CM,
GA, GN, GQ, GW, ML, MR, NE, SN, TD, TG).

Published:

— with international search report

— before the expiration of the time limit for amending the
claims and to be republished in the event of receipt of
amendments

For two-letter codes and other abbreviations, refer to the "Guid-
ance Notes on Codes and Abbreviations" appearing at the begin-
ning of each regular issue of the PCT Gazette.

BEST AVAILABLE COPY

Ta-
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(54) Title: SURFACE BASE-COAT FORMULATION FOR METAL ALLOYS

(57) Abstract: Chromium-free coating composition with anti-corrosion and anti-fingerprint properties, particularly suitable for
metal alloys, especially galvanized steel, and coated articles. Composition comprises aqueous-resin emulsion, hazardous air pol-
lutant-free co-solvent, organo-functional silane, metal chelating agent, and chromium-free corrosion inhibitor, and optionally pH
adjusting agent.

WO 03/070534 PCT/US03/06609

SURFACE BASE-COAT FORMULATION FOR METAL ALLOYS

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a coating for metal alloys. More specifically,
the present invention relates to a chrome-free coating for protecting metal alloys
from deterioration and corrosion.

2. Background Art

It is well known in the art that galvanized steel must be protected from
oxidation. Various methods have been developed for protecting against oxidation.
Some examples include chromate treatment technology and electrolytic chromate
treatment technology. However, one problem with these methods is that the
methods are unable to form a chromate film on metals simply by coating the metals
and then drying.

Unlike reactive chromate treatment technology and electrolytic chromate
treatment technology, dry-in-place chromate treatment technology is able to form a
chromate film on metals simply by coating the metals and then drying. As a result, a
distinguishing feature of dry-in-place chromate treatment is that it is not limited to
particular metal substrates. As a result, dry-in-place chromate treatment is frequently
used to impart corrosion resistance to metal surfaces to improve their adherence to
resins and most importantly to improve paint adherence and post-painting corrosion
resistance when painting is carried out.

At the present time, the main metals used in flat sheet structures are
zinciferous-plated steel sheet, aluminum, and aluminum alloy flat sheet. These are
widely used in such economic sectors as automotive applications, household
electrical appliances, building materials, and so forth. These materials are almost
inevitably subjected to a chromate treatment due to contemporary demands for high
added value.

A distinguishing feature of dry-in-place chromate treatment technology is that
it is not limited to particular metal substrates. However, this technology has other
advantages. Because a desirable film is obtained through just a simple application
step, there is no specific requirement for long reaction times, and simple equipment
can be used, so that the line length can be reduced. Moreover, the effluent

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treatment load is light because a post-treatment water rinse is not required. Also,
because dry-in-place films usually contain a higher proportion of corrosion-inhibiting
hexavalent chromium than do reactive chromate and electrolytic chromate films, dry-
in-place chromate films can provide a higher corrosion resistance than the other two
types at the same add-on weight.

The corrosion-inhibiting hexavalent chromium is soluble in the water of wet
corrosive ambients. One drawback to dry-in-place chromate films is that they are
generally more soluble in water than reactive or electrolytic chromate films. The
main component exhibiting water solubility in dry-in-place chromate films is the
hexavalent chromium ions, and films exhibiting a high water solubility of this type are
denoted below as "low-fixed-chromium" films. As is well known, the hexavalent
chromium ions are pollutants, and this fact has generally created demand for a
sparingly water-soluble dry-in-place chromate film having a high proportion of fixed
or immobilized chromium.

In addition to the problem of environmental pollution, the low proportion of
fixed chromium in dry-in-place chromate films creates other problems for industrial
application. One such problem is that the alkaline degreasing process elutes
hexavalent chromium. A degreasing step is generally required during the conversion
of dry-in-place chromated metal stock into finished product. The degreasing step
takes place in downstream channels in order to remove contaminants, such as oil,
dust, iron powder, and the like, that have been picked up during various stages and
of course during press forming. Since traditional solvent degreasing is in the course
of being discontinued due to global environmental issues, waterborne degreasing,
such as alkaline degreasing, normally must be employed for this purpose. The
elution of a portion of the dry-in-place chromate film by alkaline degreasing requires
the installation of special effluent treatment facilities in order to treat the hexavalent
chromium ions in the spent degreasing bath.

Another problem occurs when waterborne resin coatings are applied on dry-
in-place chromated stock. A very recent trend with flat sheet metal stock is that the
stock is increasingly being painted with organic resin at the manufacturing stage in
order to obtain various characteristics such as corrosion resistance, fingerprint
resistance, lubricity, and insulating characteristics. Again, in the case of organic
resins, solvent-based resins are being replaced by waterbprne resins for the same

WO 03/076534 PCT/US03/06609

environmental reason as above. The hexavalent chromium ions eluted from dry-in-
place chromate coatings inhibit dispersion of the waterborne resin in such
waterborne resin coatings. This either prevents normal application and formation of
the resin coating or ends up gelling the resin coating bath itself.
5 The reasons outlined above have prompted strong demand for the

appearance of a dry-in-place chromate treatment bath that provides a sparingly
water soluble film, i.e., a "high-fixed-chromium" film.

3+

Dry-in-place chromate treatment baths generally take the form of Cr -
containing aqueous chromic acid or dichromic acid solutions, and several methods

io have already been proposed that provide sparingly water-soluble dry-in-place
chromate films using such baths.

Japanese Examined Patent Application [Kokoku] Number Sho 61-58552
[58,552/1986] discloses a method that uses a chromating bath based on chromic
acid, chromic acid reduction product, and silica sol. However, the hexavalent

15 chromium in the chromate film is still readily eluted when a surface-treated steel
sheet bearing a chromate film formed by this method is submitted, during processing
and painting operations, to a pre-paint alkaline rinse. This causes the corrosion
resistance of the film to decline.

Japanese Patent Application Laid Open [Kokai or Unexamined] Numbers Sho

20 58-22383 [22,383/1983] and Sho 62-83478 [83,478/1987] teach the use of a silane
coupling agent to reduce hexavalent chromium ions in the chromate treatment bath.
In each case the coatings afforded by these methods have an excellent paint film
adherence. However, the chromate film afforded by the former method has a poor
alkali resistance, because it is laid down from a phosphoric acid-free chromate

25 treatment bath. The chromate film afforded by the latter method also has a similarly
inadequate alkali resistance.

Japanese Patent Application Laid Open [Kokai or Unexamined] Number Sho
63-96275 [96,275/1988] teaches a treatment method that uses a chromate
treatment bath containing organic resin whose molecule has been functionalized

30 with specific amounts of hydroxyl group. The alkali resistance is again often
inadequate in this case because the organic resin in the chromate coating formed by
this method contains carboxyl moieties produced by oxidation by chromic acid. In
addition, the treatment bath stability in this case is strongly impaired because the

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reaction of the hydroxyl-functional organic resin and chromic acid proceeds even in
the treatment bath itself.

Japanese Patent Publication [Kokoku] Number Hei 7-33583 [33,583/1995]
teaches a chromate treatment method that uses a chromate treatment bath
5 containing carboxylic acid and/or a carboxylic acid derivative. This chromate
treatment bath affords only an inadequate improvement in application performance.
In addition, because baking at 150° C to 300° C is required, this method entails
substantial cost for its heating facilities, which runs counter to the current trend of
economizing on energy. Thus, drying temperatures not exceeding 100° C are
10 desirable in order to fully exploit the overall merits of dry-in-place chromate
treatment systems.

As has been described above, the prior dry-in-place chromate treatment
baths and treatment methods have suffered from a number of drawbacks, and a dry-
in-place chromate treatment bath and treatment method that would be free of these

15 drawbacks has remained heretofore unknown. In other words, to date there has yet
to appear a dry-in-place chromate treatment bath and corresponding treatment
method that provide a good application performance and bath stability while also
providing metal surfaces with a sparingly water soluble chromate film with a good
alkali resistance, water resistance, corrosion resistance, and paint film adherence.

20 Rust-proof properties have conventionally been imparted to cold-rolled steel

sheets, galvanized steel sheets, zinc-based alloy-plated steel sheets, and aluminum-
plated steel sheets used for automobiles, electrical appliances, building materials,
and the like, usually by coating their surfaces with chromate layers. Chromating
treatment includes electrolytic chromating and application chromating. Electrolytic

25 chromating is accomplished, for example, by using a bath composed mainly of
chromic acid and also containing other anions such as sulfate, phosphate, borate,
and halogens, for treatment of the metal sheet by cathodic electrolytic treatment.
Application chromating is designed in consideration of the problem of elution of
chromium from chromated metal sheets, and it thus involves preparation of a

3 o treatment solution by adding an inorganic colloid or inorganic anion to a solution with
a portion of the hexavalent chromium portion reduced to trivalent chromium
beforehand or to a solution with a specified ratio of hexavalent chromium to trivalent

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chromium, and immersing the metal sheet therein or spraying the metal sheet with
the treatment solution.

Those chromate layers formed by electrolysis do not have sufficient corrosion
resistance despite the low elution of hexavalent chromium and there is particular
5 • loss of corrosion resistance in cases where considerable layer damage occurs
during working, etc. On the other hand, while metal sheets coated with application
chromated layers have high corrosion resistance and especially high excellent
corrosion resistance of worked sections, elution of hexavalent chromium from the
chromate layers has been a problem. Elution of hexavalent chromium can be
10 considerably reduced by coating with organic polymers, but this is still inadequate.
Although an improvement in reducing elution of hexavalent chromium can generally
be achieved by a method known as resin chromating treatment, such as disclosed in
Japanese Unexamined Patent Publication No. 5-230666, it is still impossible to avoid
trace elution.

15 Thus, in order to completely inhibit elution of hexavalent chromium, it is

necessary to develop a corrosion-resistant layer that uses absolutely no hexavalent

One previous anti-corrosion technique for incorporating absolutely no
hexavalent chromium is a method under development that uses an organic-based

20 corrosion inhibitor. The presently known ( organic-based corrosion inhibitors include
carboxylates such as benzoates, azelates, etc. and compounds containing --S-, -
N — (which readily interact with metal ions), as well as complexes thereof.

Techniques for including organic-based corrosion inhibitors in layers have
been proposed. Examples of such layers include the hydrooxime complex of zinc

25 disclosed in Japanese Unexamined Patent Publication No. 62-23989, the metal
chelate compounds of Mg, Ca, Ba, Zn, Al, Ti, Zr, Sn, Ni, etc. disclosed in Japanese
Unexamined Patent Publication No. 3-183790 and Japanese Unexamined Patent
Publication No. 2-222556, the alkali earth metal salts, transition metal salts, and
transition metal complexes of organic compounds disclosed in Japanese

30 Unexamined Patent Publication No. 6-321851 and the titanium and zirconium
complexes of carboxylic acids disclosed in Japanese Unexamined Patent
Publication No. 8-48916. These corrosion inhibitors, however, have weak anti-
corrosion effects due to the metal elements forming the complexes and thus have

chromium.

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failed to provide the same function as hexavalent chromium. In particular, almost
no corrosion resistance can be expected at damaged sections or at the locations of
layer defects produced during working.

Japanese Unexamined Patent Publication No. 7-188951 discloses a rare
earth metal-organic chelate compound for the purpose of inhibiting corrosion of
metals that contact solutions, such as radiators or pipes. This corrosion inhibitor was
designed as a water-soluble compound, to allow continuous provision of the
corrosion inhibitor to corrosion sites by circulation of the solution. Consequently,
although the strong anti-corrosion effect of the rare earth metal element is utilized,
with layers on metal sheets wherein the absolute amount of corrosion inhibitor onto
the corrosion sites is limited by the coating coverage, elution occurs out of the layer
in humid atmospheres so that long-term corrosion resistance comparable to
chromate layers cannot be achieved.

An example of an anti-corrosive layer is a magnesium alloy materials.
Magnesium alloy materials have the lightest weight among the practical metallic
materials. Magnesium alloy materials also have a large specific strength and a good
castability. Wider application of the materials to cases, structural bodies, various
parts, etc. of household appliances, audio systems, aircrafts, automobiles, etc. has
been desired. Particularly, Al-containing AZ91D (Al: 8.3-9.7wt. %) and AM60B (Al:
5.5-6.5 wt. %) have a good fluidity in die-casting and thixo molding and thus are
most desirable alloys.

However, magnesium has the most basic normal electrode potential among
the practical metallic materials resulting in high corrosion susceptibility when the
metal is brought into contact with other metals and a considerably poor anti-
corrosiveness in an aqueous acidic, neutral, or chloride solution. For its application
to corrosion-excluding positions, e.g. good appearance-maintaining positions etc., it
is necessary to provide an anticorrosive treatment. The thin coat and conductive
layer are preferred. Coatings are the most popular anti-corrosion means, but it is
hard to apply coatings to magnesium alloy materials per se because of the
disadvantage that the resulting coating film has poor adhesiveness. Sometimes,
corrosion may occur under the coating film, and thus it is the ordinary practice to
conduct a substrate surface treatment in advance of the coating process.

The substrate surface treatment technology includes, for example, substrate

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surface, treatments of forming a metal oxide film or a sparingly soluble salt film by
chemical conversion treatment or anodizing using such heavy metal oxo acid salts
as chromates, permanganates, or phosphates so as to improve the corrosion
resistance and the adhesiveness of coating films. The chemical conversion coatings
5 generate a large amount of wastewater and toxic chemical contaminants.

It is also the ordinary coating practice to use oil paints and synthetic resin
paints that contain lead compounds, zinc powder and its compounds, chromates,
etc. as an anticorrosive pigment.

Processes for forming an anticorrosive film on a magnesium alloy are

10 disclosed in JP-A-9-1 76894 and JP-A-9-228062.

Surface treatments using specific chemical compounds such as chromates
and permanganates have problems relating to environmental friendliness, such as
effluent water pollution problems and skin allergy problems for operators. The use of
such surface treatments is increasingly subject to strict regulations. Phosphates are

15 also more or less harmful to the environment and the corrosion resistance of
resulting phosphate films is not satisfactory. The salt (fog) spray test (ASTM B117)
shows corrosion in 24 hours. Substitute processes for such substrate surface
treatments are under development but these methods still have problems with
respect to corrosion resistance.

20 Lead compounds or chromates contained as anticorrosive pigments in

coating technology have problems relating to environmental friendliness.
Furthermore, there are occasionally problems relating to corrosions. These
problems are due to diffusion of oxygen or water generated by corrosion present
under the coating film or by coating film defects.

25 The invention disclosed in Japanese patent JP-A-9-1 76894 relates to an

electrolytic treatment. Anodizing requires a power source of high voltage. An entirely
uniform film is hard to obtain. The patent discloses treatments using an organometal
that are highly reactive and thus an entirely uniform film is likewise hard to obtain.

It would be useful to develop an alloy coating that is easy to apply,

30 environmentally friendly, and anti-corrosive. The preferred coating is a water-based
system containing no carcinogenic chromates and no hazardous air pollutant (HAP)
co-solvents.

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SUMMARY OF THE INVENTION

According to the present invention, there is provided a metal alloy coating
composition, the coating having a chrome-free environmentally friendly formulation.
The coating can be used as an anti-corrosion coating and an anti-fingerprint coating.

BRIEF DESCRIPTION OF THE DRAWINGS

Figures 1A and B are photographs showing two panels coated with this
chrome- and HAP-free formulation were subjected to 120 hours of ASTM B-117
testing;

Figures 2A and B are photographs that display panels of 2024-T3
Bare/Alodine 1200 (Figure 2 A) and on 2024-T3 Bare/AFP (Figure 2B) coated with
AD931 8/AD2298 primer after a 1 000 hour salt spray test; and

Figure 3 shows the Bode-magnitude plots (frequency vs. impedance) of
AD9318/AD2298 coated on 2024-T3 Bare/AFP panels after soaking in 3% NaCI
solution for 72 hours (♦) and 1000 hours (▲), and those on 2024-T3 Bare/Alodine
1200 panels soaked for 72 hours (•) and 1000 hours (■).

DESCRIPTION OF THE INVENTION

Generally, the present invention provides a metal alloy coating. The coating
is an emulsion that contains only environmentally friendly materials. The coating is
able to meet all quality control standards with regard to electrical resistance,
corrosion resistance, abrasion resistance, and adhesion to metal surface and
topcoat (liquid and powder paints).

The present invention provides a chrome-free, water-based, and hazardous
air pollutant (HAPs)-free formulation for a pretreatment coating. The coating can be
applied before any primers and topcoats are applied to a surface. These surface
pretreatment coatings have excellent protective performance (alkaline and salt spray
resistances) for galvanized steel (electrogalvanized and hot-dip, and galvalume),
magnesium alloys (such as AZ31, AM20), titanium alloys (such as Ti-6AI-4V), and
aluminum alloys (such as 2024-T3, 7075-T6), and other similar alloys for surface
pretreatment and corrosion protections. The galvanized steel, and magnesium,
titanium, and aluminum alloys are currently used in computer, cellular phone,
notebook, bicycles, and aerospace industries. These surface coatings also offer a
superior property for adding primers and/or topcoats.

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More specifically, the coating of the present invention includes the following:
60-70% by weight of water, 15-25% by weight of resins, 10-20% by weight
hazardous air pollutants (HAPs)-free co-solvents (such as dipropylene glycol normal
butyl ether - DPnB, propylene glycol normal butyl ether - PnB), 0.4-5% by weight
organofunctional silanes (such as functionalized mercaptosilianes, functionalized
aminosilanes, functionalized vinylsilanes), 0.1-1.0% by weight corrosion inhibitors,
0.1-1.0% by weight metal chelating agents, and a trace amount of pH adjusting
agents. A specific example of a surface base-coat formulation is as follows: the
chrome-free, HAPs-free, and water-based emulsion contains 94 g water, 32 g acrylic
co-polymer resin, 25 g HAPs-free co-solvents, 0.54 g chrome-free corrosion
inhibitors, 0.2 g metal chelating agents, 0.27 g pH adjusting agents, and 3 g
functionalized silanes.

The term "resin" includes, but is not limited to, acrylic emulsion, polyurethane
emulsion, co-polymer emulsion, and other similar compounds. This list is included
to exemplify the resins that can be used. The list is not intended to be exhaustive.
Those of skill in the art know additional resins that are of a sub-micrometer or
nanometer particle size that can be utilized in the present invention.

The phrase "organofunctional silanes" as used herein is intended to include,
but is not limited to, silanes that are sterically hindered substituents located at silicon
atoms. Preferably, the functional groups are vinyl, epoxy, sulfur, amino, and other
similar groups. This list is included to exemplify the organofunctional silanes that can
be used. The list is not intended to be exhaustive. Those of skill in the art know
additional organofunctional silanes that can be utilized in the present invention.

By "corrosion inhibitor" as used herein, the phrase is intended to include, but
is not limited to, silicates, vanadates, metaborates, manganates, phosphates,
mercapto-compounds, xanthic acid salts, dithiocarbamic acid salts, organic
carboxylates, and other similar compounds. This list is included to exemplify the
corrosion inhibitors that can be used. The list is not intended to be exhaustive.
Those of skill in the art know additional corrosion inhibitors that can be utilized in the
present invention.

The phrase "pH adjusting agent" as used herein is intended to include, but is
not limited to, the following agents: ammonia, organic amines, and other similar
agents. This list is included to exemplify the pH-adjusting agents that can be used,

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the list is not intended to be exhaustive. Those of skill in the art know additional pH
adjusting agents that can be utilized in the present invention.

The term "protection" as used herein means that the coating composition
forms a layer inhibiting oxidation of the underlying surface and resisting the alkaline
solution washing (or degreasing). The coating of the present invention is able to
protect the underlying surface from corrosion. For example, when the coating of the
present invention was applied to a surface, no corrosion is detected after 96 hours in
salt (fog) spray test (ASTM B1 17). The coating shows no removal of paint film after
subjecting to 2-3% trisodium phosphate solution at 65 oC for 3-5 minutes.

The coating formulation of the present invention is preferably applied to the
surface of a metal alloy substrate using techniques known to those of skill in the art.
The preferred magnesium alloy substrate for use in the present invention has
excellent forgeability to form a thin casing with sharp bottom edges, corners and
projections whose inner surfaces preferably have radii of curvature of about 2 mm or
less, particularly about 1 mm or less. Preferably, the magnesium alloy used in the
present invention has a composition of 1-6 weight percent of Al, 0-2 weight percent
of Zn and 0.5 weight percent or less of Mn, the balance being substantially Mg and
inevitable impurities.

When the amount of aluminum is less than one weight percent, the
magnesium alloy has poor toughness, though it is well forgeable. On the other hand,
when the amount of aluminum is more than six weight percent, the magnesium alloy
has poor forgeability and corrosion resistance. The preferred amount of aluminum is
two to four weight percent, particularly about three weight percent.

Zinc has similar effects as those of aluminum. From the aspect of forgeability
and metal flow, Zn is preferably zero to two weight percent. The preferred amount of
Zn is zero to one weight percent.

If added in a small amount, magnesium functions to improve the
microstructure of the magnesium alloys. From the aspect of mechanical properties,
magnesium is preferably 0.5 weights percent or less.

The magnesium alloy can contain other elements such as rare earth
elements, lithium, zirconium, etc., in such amounts as not to adversely affect the
forgeability, mechanical strength, etc. of the magnesium alloys, usually in a total
amount as small as 0.2 weight percent or less.

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The magnesium alloys satisfying the above composition requirements are
commercially available as AZ31 (Al: about 3 weight percent, Zn: about 1 weight
percent, Mn: 0.2-0.3 weight percent, Mg and inevitable impurities: balance), AM20
(Al: about 2 weight percent, Mn: about 0.5 weight percent, Mg and inevitable
impurities: balance), etc., in ASTM.

The magnesium alloy body is preferably formed into a thin forged casing by at
least two steps. In a preferred embodiment, the forging comprises a first forging step
and a second forging step. If necessary, a further forging step can be added
between the first and second forging steps.

The first forging step involves shaping the body. The magnesium alloy body
can be in any shape such as rectangular parallelepiped, cylinder, etc., as long as it
is forgeable to a desired shape. However, it has been found that when the
magnesium alloy body is in a thick bulk shape, the resultant forged product has flow
marks on the surface. The term "flow marks" means marks indicating traces of
plastic flow of the magnesium alloy occurring during the forging process.

When a thin magnesium alloy body is forged at a low compression ratio, the
flow marks can be suppressed, because disturbed plastic flow does not occur at a
low compression ratio. The term "compression ratio" used herein means a ratio
(percentage) expressed by the formula: [(to -tf)/to ]x100%, wherein to is an original
thickness of the magnesium alloy body to be forged, and tf is a thickness of the
forged product.

A compression ratio is preferably within 75% in the first forging step and
within 30% in the second forging step to sufficiently suppress the flow marks on the
resultant thin forged casings. To achieve the above compression ratios, the
magnesium alloy body is preferably in a thin plate shape having a thickness of about
3 mm or less. With such a thin magnesium alloy plate, the mechanism of plastic flow
can be utilized to produce a thin forged casing with no flow marks. Because the
original surface conditions of the magnesium alloy plates are substantially kept on
the forged products, it is preferable to use the magnesium alloy plates with
extremely small surface roughness. In the case of a round magnesium alloy rod, the
compression ratio can usually be more than 80%.

In the case of forming a forged casing of about 1.5 mm or less in thickness,
with an anodic oxidation coating for exhibiting metallic glow, it is important to forge a

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thin magnesium alloy plate of about 3 mm or less, preferably about 2 mm or less,
particularly about 1-1 .5 mm in thickness.

Though the size of the magnesium alloy plate can be determined depending
on the compression ratio, it is preferable that the magnesium alloy plate is equal to
5 or slightly larger than a bottom area of the final thin forged casing. When the
magnesium alloy plate is too large, the resultant thin forged casings are likely to
have wrinkles at bottom edges and corners, lowering the yield of the final products.
On the other hand, when the magnesium alloy plate is too small, the resultant thin
forged casings are unlikely to be uniform in thickness in peripheries.

10 The magnesium alloy body to be forged is first preheated uniformly at a

temperature of 350-500° C, slightly higher than the forging temperature of the
magnesium alloy body. The preheating temperature of the magnesium alloy body is
defined herein as a temperature of atmosphere inside an electric furnace in which
the magnesium alloy body is heated.

15 If the preheating temperature is lower than 350° C, the magnesium alloy does

not smoothly flow into the die cavity during the forging process, thus failing to make
the thickness of the resultant forged casing as small as about 1 .5 mm or less. If the
preheating temperature is higher than 500° C, the magnesium alloy body is totally or
partly melted, resulting in extreme metal flow marks appearing on the surface, which

20 makes it impossible to obtain a thin forged casing with high quality. Also, a higher
temperature causes excessive oxidation and even burning of the magnesium alloy
during the forging process. The preferred preheating temperature of the magnesium
alloy body is 350-450° C, particularly 400-450° C.

25 alloy body is severely oxidized, adversely affecting the forgeability, corrosion
resistance, and surface appearance of the resultant thin forged casing. The
preheating of the magnesium alloy body is carried out in vacuum or in an inert gas
atmosphere such as an argon gas, etc.

30 alloy body. For instance, it is about 10-20 minutes for a cylindrical magnesium alloy
body of 30 mm in diameter and 10-30 mm in length. If the magnesium alloy body
were in a thin plate shape of about 3 mm or less in thickness, the preheating time
would be sufficient to be as short as 5-15 minutes.

If the magnesium alloy body is heated in the air, a surface of the magnesium

The preheating time is determined depending on the size of the magnesium

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PCT/US03/06609

The first forging step can be carried out on the magnesium alloy body under
conditions of a die temperature of 350-450° C, a compression pressure of 3-30
tons/cm 2 , a compressing speed of 10-500 mm/sec, and a compression ratio of 75%

the die temperature is lower than 350° C, the preheated magnesium alloy body is so
cooled by contact with the die that sufficient metal flow cannot be achieved during
the first forging step, resulting in rough forged surface. On the other hand, when the
die temperature is higher than 450° C, the forged product cannot easily be removed
10 from the die. The preferred die temperature is 360-420° C. The first forging
temperature is about 50-80° C lower than a temperature at which the magnesium
alloy starts melting to prevent the magnesium alloy from melting locally during the
first forging step.

15 die blocks is 3 tons/cm 2 or more. When the compression pressure is less than 3
tons/cm 2 , the resultant intermediate forged product cannot be made fully thin. The
upper limit of the compression pressure can usually be determined based upon the
compression ratio. Too high compression pressure causes damage to the edges of
the die. In addition, even though the compression pressure exceeds 30 tons/cm 2 ,

20 further improvements in the quality of the forged products cannot be obtained. The
upper limit of the compression pressure is 30 tons/cm 2 . The preferred compression
pressure in the first forging step is 5-25 tons/cm 2 .

The compressing speed of the magnesium alloy body can be 10-500 mm/sec.
When the compressing speed is less than 10 mm/sec, the productivity of the

25 intermediate forged products is too low. When the compressing speed is more than
500 mm/sec, metal flow cannot follow the compression of the magnesium alloy
body, resulting in disturbed metal flow, which leads to extreme flow marks on the
surface of the body. The preferred compression speed in the first forging step is 50-
300 mm/sec.

30 The compression ratio is preferably within 75% in the first forging step to

sufficiently suppress the flow marks on the resultant intermediate forged products. If
the compression ratio exceeds 75%, it is difficult to prevent the flow marks from
appearing on the surfaces of the resultant intermediate forged products. The more

or less.

5

The die temperature is almost equal to the first forging temperature. When

The pressure at which the magnesium alloy body is compressed by a pair of

13

WO 03/076534 PCT/US03/06609

preferred compression ratio in the first forging step is 50-50%, particularly 18-45%.
The forging can be carried out mechanically or hydraulically.
The second forging step includes preheating the intermediate forged product.
The intermediate forged product obtained in the first forging step is preheated
5 uniformly at a temperature of 300-500° C in vacuum or in an inert gas atmosphere
such as an argon gas, etc. If the preheating temperature of the intermediate forged
product is lower than 300° C, smooth metal flow does not occur along the cavity
surface of the forging die during the second forging step, thereby failing to precisely
transfer the cavity surface contour of the second forging die to the final thin forged
10 casing. If the preheating temperature is higher than 500° C, the intermediate forged
product can be melted in portions subjected to strong friction, resulting in extreme
flow marks appearing on the surface. The preferred preheating temperature of the
intermediate forged product is 350-450° C.

The preheating time of the intermediate forged product is also determined
15 based upon the size of the intermediate forged product. For instance, it is about 5-15
minutes for the intermediate forged product of 1 mm in thickness.

The second forging step is preferably carried out on the intermediate forged
product under the conditions of a die temperature of 300-400° C, a compression
pressure of 1-20 tons/cm 2 , a compressing speed of 1-200 mm/sec, and a
20 compression ratio of 30% or less.

The die temperature is almost equal to the second forging temperature but
can be slightly lower than the first forging temperature because the compression
ratio is smaller in the second forging step than in the first forging step. When the die
temperature is lower than 300° C, the preheated intermediate forged product is sb
25 cooled by contact with the die that cavity surface contour cannot be precisely
transferred from the second forging die to the resultant thin forged casing by the
second forging step. When the die temperature is higher than 400° C, the forged
product cannot easily be removed from the die. Therefore, the preferred second die
temperature is 330-400° C.
30 The compression pressure in the second forging step can be smaller than in

the first forging step, and is preferably 1-20 tons/cm 2 . When the compression
pressure is less than 1 tons/cm 2 , the resultant forged casing cannot be made fully
thin with excellent surface contour. When the compression pressure exceeds 20

14

WO 03/076534 PCT/US03/06609

tons/cm 2 , further improvements in the quality of the forged products cannot be
obtained. The preferred compression pressure in the second forging step is 5-15
tons/cm 2 .

The compressing speed of the intermediate forged product can be 1-200
5 mm/sec. When the compressing speed is less than 1 mm/sec, the productivity of the
forged casings is too low. When the compressing speed is more than 200 mm/sec,
the cavity surface contour of the second forging die cannot be precisely transferred
to the thin forged casing, failing to provide the thin forged casing with excellent
surface conditions. The preferred compression speed in the second forging step is

10 20-100 mm/sec.

The compression ratio is preferably within 30% in the second forging step to
sufficiently suppress the flow marks on the resultant thin forged casings. If the
compression ratio exceeds 30%, it is difficult to prevent the flow marks from
appearing on the surfaces of the resultant thin forged casings. The more preferred

15 compression ratio in the second forging step is 5-20%.

In one embodiment, the thin forged casing of the present invention can be a
box-shaped, thin plate that has projections of various heights on either or both
surfaces. The thickness of the thin plate in areas without projections is preferably as
small as about 1.5 mm or less, more preferably about 1 mm or less. The projections

2 0 can be bosses for screw holes, projections indicating alphabets, numbers and/or
symbols, etc. Of course, the thin plate portion can have thinner regions than the
remainder unless the thinner regions affect the mechanical strength of the thin
forged casing.

The thin forged casing of the present invention preferably has sharp bottom
25 edges, corners and projections. Particularly in the case of small casings, for
instance, those of minidisks, the inner surfaces of bottom edges and comers
preferably have radii of curvature of 1 mm or less. Sharp bottom edges, corners, and
projections whose inner surfaces have such small radii of curvature can be provided
only by the forging method of the present invention.
30 The resultant thin forged casing is trimmed at sidewalls by a cutter, etc. such

that the sidewalls have exactly the same height. If necessary, screw bores can be
formed in the boss projections. The thin forged casing can then be polished.

After polishing, the thin forged casing is subjected to a surface coating such

15

WO 03/076534 . PCT/US03/06609

as an anodic oxidation coating, a paint coating, etc. and the anti-corrosion coating
of the present invention. In the present invention, a chrome-free and HAPs-free
aqueous emulsion is preferred. The coating can be applied in any manner known to
those of skill in the art. Examples of such techniques include, but are not limited to,
5 spraying the coating on the surface to be coated, dipping the surface in the coating
composition, and painting the coating on the surface to be coated.

The anodic oxidation coating can be applied using methods known to those of
skill in the art. An electrolytic solution for anodic oxidation can have a composition
comprising one or more of sodium dichromate, acidic sodium fluoride, acidic
10 potassium fluoride, acidic ammonium fluoride, ammonium nitrate, sodium
dihydrogenphosphate, ammonia water, etc. The electrolytic components can be
combined depending on the composition of the magnesium alloy, the desired color
of the thin forged casing, etc.

Because the anodic oxidation coating is generally transparent with or without
15 tint, the anodized thin forged casing keeps metallic gloss inherent in the magnesium
alloy.

Though the paint coating can be applied with any paint, it is preferable to coat
a clear paint if metallic gloss is desired. The clear paint can be made of
thermosetting acrylic resins, polyester resins, epoxy resins, etc. without or trace of

20 pigments like clear coatings of automobiles, etc. Before coating, the thin forged
casing is preferably subjected to a surface base-coat of aqueous emulsion with the
anti-corrosive treatment of the present invention. The anti-corrosive coating is
applied as a single coat on the surface of the magnesium alloy. The coated alloy is
thermally cured at approximately 125° C for three to five minutes. The dry film of

25 final coating is approximately 1.6 ^m thick with a resistance of approximately 0.3a.
The coating provides an excellent metal surface (and top coat) adhesion and can
pass a salt spray test of >72 hours that is superior to those chemical conversion
coatings known in the prior art.

The invention is further described in detail by reference to the following

30 experimental examples. These examples are provided for the purpose of illustration
only, and are not intended to be limiting unless otherwise specified. Thus, the
invention should in no way be construed as being limited to the following examples,
but rather, should be construed to encompass any and all variations which become

16

* WO 03/076534 PCT/US03/06609

. evjdent as a result of the teachings provided herein.

EXAMPLES

Example 1 =

A chemically pretreated galvanized or zinc-alloy-plated steel sheet is
5 commonly used to inhibiting corrosions of steel substrates. The processed
galvanized steel has poor fingerprint resistance and earthing properties. The
corrosion inhibition galvanized steel is also poor, leading to the formation of white
rust covered the entire zinc coated steel in less than 24 hours in a salt (fog) spray
test (ASTM B-117). The galvanized steel is utilized in large quantity for electronic

10 parts, equipment or the like that require good fingerprint resistance, earthing
properties, and corrosion resistance. In current industrial practice, the ultra thin
organic coatings (about 1 micrometer thick) are generally applied on high-speed
lines. This desired organic coating should have excellent anti-fingerprinting
characteristics, resist to alkaline solution (i.e. 2% tri-sodium phosphate solution at 65

15 degrees C for 2 minutes) and passes a 120 hours salt (fog) spray test (ASTM B1 1 7).
These chrome- and HAP-free anti-fingerprint coatings have been tested at different
independent laboratories, and have been shown to pass both alkaline solution
washing and 120 hours salt (fog) spray tests. Two panels coated with this chrome-
and HAP-free formulation were subjected to 120 hours of ASTM B-1 17 testing at the

20 China Steel Corporation and are shown in Figures 1A and B. Figure 1A was tested
without alkaline solution washing, and Figure 1B was tested after 2 minutes of
alkaline washing at 65 °C.

The most commonly used coating formulation in today's industrial practice is
a water-based organic composite coating that contains water, resins (acrylic

25 emulsion, polyurethane emulsion, co-polymer emulsion, etc.), isopropyl alcohol (co-
solvent), and a large quantity of hexavalent chromates (corrosion inhibitors). This
coating formulation works extremely well, but the hexavalent chromates are toxic
and carcinogenic that cause lung cancer, and kidney and liver damage, and
isopropyl alcohol is considered as hazardous air pollutants (HAPs). When OSHA

30 implements the projected stringent limits within the next few years, many chromate
prier end-users will find it difficult to comply with worker exposure limits and
environmental safety.

The competition and challenge started several years ago for developing the

17

PCT/US03/06609

. WO 03/076534

chrome-free and HAPs-free water-based anti-fingerprint coatings on galvanized
steel for using on high-speed lines. There is no satisfactory formulation known
currently that passes the required properties and that are chrome-free and HAPs-
free. This invention is described for the first time, chrome-free and HAPs-free water-
5 based anti-fingerprint coatings that pass all required tests. The coating formulations .
contain 60-70% by weight of water, 15-25% by weight of resins (sub-micrometer or
nanometer size resin particles, e.g. acrylic emulsion, polyurethane emulsion, co-
polymer emulsion, etc.), 10-20% by weight of HAPs-free co-solvents, 0.5-5% of
organofunctional silanes sterically hindered substituents at silicon atoms (the
10 functional groups are vinyl, epoxy, sulfur, amino, etc.), 0.1-1.0% corrosion inhibitors
(silicates, vanadates, manganates, phosphates, organic carboxylates, etc.) and a
trace amount of pH adjusting agents (ammonia, organic amines, etc.).
Example

15 to their favorable strength to weight ratio, such as AZ91 and ZE41 . However, it is
the corrosion resistance that often limits the applications of magnesium-based
alloys. Furthermore, the surface of a magnesium alloy is known to be very difficult to
coat. Even with the chromic acid (toxic and carcinogenic) treatment applied* it
causes serious problems such as insufficient adhesive strength resulting from a

20 release agent and unevenness of treatment involved and inadequate corrosion
resistance incurred from slight impurities contained in the materials.

The current surface treatment processed for magnesium alloys are chromate
conversion coating non-chromate (i.e. manganate, vanadate, stannate, etc.)
conversion coating, cold phosphate conversion coating, and galvanic anodizing

25 treatment. The processes involve multiple steps and are error-prone and costly.
The multi-step surface treatment technologies produce waste including organic
solvents, heavy metals, and other toxic and deleterious materials.

Applicants have used a green chemistry approach and developed an
aqueous emulsion coating for surface treatment of magnesium alloys. The emulsion

30 contains only environmentally safe chemicals, and precursors hybridized of acrylic
co-polymers and silanes.

A single-coat application of "Acryl-Mg-Sol" on magnesium alloy surface,
followed by a thermal curing at 150 degrees C for 5 minutes has shown to give a dry

Magnesium-based alloys are of interest for many industrial applications due

18

•

PCT/US03/06609

WO 03/076534

film thickness of approximately 1.6 u.m with a resistance of ~0.3 mo/cm. The
protective film displays an excellent metal surface adhesion (5B, ASTM D3359), and
has passed a salt (fog) spray test (ASTM B117) of >24 hours that is superior to a
multi-step chrome (or dichromate) pickle treatment.

5 FvamplA 3:

The AFP (anti-fingerprint coating) was developed recently in applicant's lab. It
has been shown to provide excellent metal surface pretreatment on bare cold-rolled
steel (CRS), galvanized steel, magnesium alloys, and titanium alloys. Here, the AFP
system is extended and applied to the untreated 2024-T3 Bare Al coupon, by
io dipping and spinning off the excess emulsion. The pretreated Al coupon is then
thermally cured at 150 °C (oven temperature) for 1 min. to give a treated 2024-T3
Bare/AFP Al panel. A 0.8-0.9 mil dry film of AD9318/AD2298 chromate primer was
prepared on 2024-T3 Bare/AFP and 2024-T3 Bare/Alodine 1200 coupons, and
cured overnight at 49 °C. The resistance to corrosion of AFP and Alodine 1200
15 surface pretreatment on 2024-T3 Bare aluminum alloy is examined by salt spray
tests and electrochemical impedance spectroscopy (EIS) scans.

Figure 2 displays panels of 2024-T3 Bare/Alodine 1200 (photograph A) and
on 2024-T3 Bare/AFP (photograph B) coated with AD9318/AD2298 primer after a
1000 hour salt spray test. Both panels are free of white rust, field blisters, white pits,
20 or other undesirable defects. The photograph shown in Figure 2A (Alodine 1200
panel) shows stains along the X-scribe area.

The photograph shown in Figure 2B (AFP panel) is free of stain. A slight
discoloration (i.e., a leaching of chromate anti-corrosive pigments) is observed in
Figure 2A, but not in Figure 2B. This is an important observation, because the non-
25 chromate AFP surface pretreatment retains the chromate anti-corrosive pigments in
the primer, while the Alodine 1200 pretreatment does not. The ability of AFP to
retain the chromate pigments in the primer film will prolong the effect of corrosion
resistance and, more importantly, reduces the possibility of chromate contaminations
of the groundwater and environment.
30 The salt spray testing results are in good agreement with the EIS

measurements. Figure 3 shows the Bode-magnitude plots (frequency vs.
impedance) of AD9318/AD2298 coated on 2024-T3 Bare/AFP panels after soaking
in 3% NaCI solution for 72 hours (♦) and 1000 hours (A), and those on 2024-T3

19

WO 03/076534 PCT/US03/06609

3are/Alodine 1200 panels soaked for 72 hours (•) and 1000 hours (■). The paint
film of AD9318/AD2298 coated on 2024-T3 Bare/AFP panel has a slope of nearly -
1, indicating to a pure capacitor, with a high impedance value of 4 x 10 9 Q-cm 2 at
0.01 Hz (♦). This high quality of paint film protective performance is completely
5 retained after soaking in 3% NaCI solution for 1000h (A). On the other hand, the
paint film of AD9318/AD2298 coated on 2024-T3 Bare/Alodine 1200 panel shows
some stains in the salt spray test (Figure 2A) and thus gives a low impedance value
of 4 x 10 7 Q-cm 2 (•) that is 100 times lower than the painted AFP panel. A reduction
in impedance value is also observed for the painted Alodine 1200 panel after
10 soaking in 3% NaCI solution for 1 000 hours (■).

Throughout this application, author and year and patents by number
reference various publications, including United States patents. Full citations for the
publications are listed below. The disclosures of these publications and patents in
their entireties are hereby incorporated by reference into this application in order to
15 more fully describe the state of the art to which this invention pertains.

The invention has been described in an illustrative manner, and it is to be
understood that the terminology that has been used is intended to be in the nature of
words of description rather than of limitation.

Obviously, many modifications and variations of the present invention are
20 possible in light of the above teachings. It is, therefore, to be understood that within
the scope of the described invention, the invention may be practiced otherwise than
as specifically described.

20

i

WO 03/076534

CLAIMS

PCT/US03/0660'9

What is claimed is:

5 1. A coating composition comprising a chrome-free environmentally friendly
formulation.

2. The coating according to claim 1, wherein said composition includes water,
resins, hazardous air pollutants-free co-solvents, organofunctional silanes, metal
chelating agents, and chrome-free corrosion inhibitors.
10 3. The coating according to claim 2, wherein said composition further includes at
least one pH adjusting agent.

4. The coating according to claim 2, wherein said water is present in a range of 60-
70% by weight, and preferably present in a range of 61-63% by weight.

5. The coating according to claim 2, wherein said resin is present in a range of 15-
15 25% by weight and preferably in a range of 20-23% by weight is preferred.

6. The coating according to claim 2, wherein said resin is of a size selected from the
group consisting essentially of micro- and nano- particle size.

7. The coating according to claim 5, wherein said resin is selected from the group
consisting essentially of an acrylic emulsion, a polyurethane emulsion, a co-polymer

20 emulsion, and other similar compounds.

8. The coating according to claim 2, wherein said hazardous air pollutants (HAPs)-
free co-solvents are present in a range of 10-20% by weight and preferably in a
range of 15-17% by weight.

9. The coating according to claim 1 1 , wherein said hazardous air pollutants (HAPs)-
25 free co-solvents are selected from the group consisting essentially of DPnB and PnB

co-solvents.

10. The coating according to claim 2, wherein said organofunctional silanes are
present in a range of 0.4-5% by weight and preferably in a range of 1.5-2.5 % by
weight is preferred.

30 11. The coating according to claim 10, wherein said organofunctional silanes
include sterically hindered substituents located at silicon atoms.
12. The coating according to claim 11, wherein said substituents are selected from
the group consisting essentially of vinyl, epoxy, sulfur, amino, functionalized

21

WO 03/076534

PCT/US03/06609

mercaptosilanes, and aminosilanes.-

13. The coating according to claim 2, wherein said corrosion inhibitors are present
in a range of 0.1-1.0% by weight and preferably in a range of 0.3-0.5% by weight is
preferred.

5 14. The coating according to claim 11, wherein corrosion inhibitor is selected from
the group consisting essentially of silicates, vanadates, metaborates, manganates,
phosphates, mercapto-compounds, xanthic acid salts, dithiocarbamic acid salts,
organic carboxylates, and other similar compounds.

15. The coating according to claim 3, wherein said composition includes trace
10 amounts of pH adjusting agents.

16. The coating according to claim 15, wherein pH adjusting agent is selected from
the group consisting essentially of ammonia, organic amines, and other similar
agents.

17. A metal alloy coated with the coating composition as set forth in claim 1.
15 18. An anti-corrosion coating comprising the composition set forth in claim 1.

19. An anti-fingerprint coating comprising the composition set forth in claim 1.

20. A highly adhesive coating to the metal alloys and galvanized steel as set forth in
claim 1 .

21. A highly adhesive coating to the subsequent liquid and powder paints as set
20 forth in claim 1

22. The galvanized and galvalume coats with the coating composition as set forth in

claim 1 .

WO 03/076534 • PCT/US03/06609

1/3

( z uid uiqo) |zl

INTERNATIONAL SEARCH REPORT

International application No.
PCT/US03/06609

A. CLASSIFICATION OF SUBJECT MATTER

D>C(7) : C09D 5/12, B32B 15/08

US CL : see electronic DB search indicated below
According to International Patent Classification (IPC) or to both national classification and IPC

B. FIELDS SEARCHED

Minimum documentation searched (classification system followed by classification symbols)
U.S. : see electronic DB search indicated below

Documentation searched other than minimum documentation to the extent that such documents are included in the fields searched

Electronic data base consulted during the international search (name of data base and, where practicable, search terms used)
Please See Continuation Sheet

C. DOCUMENTS CONSIDERED TO BE RELEVANT

Category *

Citation of document, with indication, where appropriate, of the relevant passages

Relevant to claim No.

X
A
X
A
A
P

US 5,451,431 (PURNELL et al.) 19 September 1995 (19.09.1995), column 1, lines 10-16.

US 5,077,332 (BLATTLER et al.) 31 December 1991 (31.12.1991), column 1, lines 5-11.

US 5,879,436 (KRAMER et al.) 9 March 1999 (09.03.1999).

US 6,437,036 Bl (GESSNER et al.) 20 August 2002 (20.08.2002).

1, 17-22

1, 17-22

| | Further documents are listed in the continuation of Box C. 1 I See patent family annex.

* Special categories of cited documents:

"A" document defining the general state of the ait which is not considered to be
of particular relevance

"E" earlier application or patent published on or after the international filing date

"L" document which may throw doubts on priority claim(s) or which is cited to
establish the publication date of another citation or other special reason (as
specified)

u O" document referring to an oral disclosure, use, exhibition or other means

M P" document published prior to the international filing date but later than the
priority date claimed

later document published after the international filing date or priority
date and not in conflict with the application but cited to understand the
principle or theory underlying the invention

document of particular relevance; the claimed invention cannot be
considered novel or cannot be considered to involve an Inventive step
when the document is taken alone

document of particular relevance; the claimed invention cannot be
considered to involve an inventive step when the document is
combined with one or more other such documents, such combination
being obvious to a person skilled in the art

document member of the same patent family

Date of the actual completion of the international search
06 June 2003 (06.06.2003)

Date of mailing of the international

tnan

report

Name and mailing address of the ISA/US
Mail Stop PCT, Attn: ISA/US
Commissioner for Patents
P.O. Box 1450

Alexandria, Virginia 22313-1450
Facsimile No. (703)305-3230

Authorized officer
Vasudevan S Jagannathan
Telephone No. 703-308-0661

Form PCT/ISA/210 (second sheet) (July 1998)

INTERNATIONAL SEARCH REPORT

PCT/US03/06609

Continuation of B. FIELDS SEARCHED Item 3:

USPTO EAST (USPAT, US-PGPUB, USOCR, EPO, JPO, DERWENT, IBMJTDB)

428/425.8,447 and solvents 1 and (corrosion adj inhibit$) and (emulsion or resin$l or polymer$l) and silane$l
252/389.22,389.23,389.31,389.32 and so!vent$l and (emulsion or resin$l or polymer$l) and silane$l

Form PCT/ISA/210 (second sheet) (July 1998)

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